CSF Leak - Beta-2 Transferrin

Diagnosis

Indications for Testing

• Presence of otorrhea or rhinorrhea
• Patient with recurrent episodes of meningitis

Laboratory Testing

• Chemical analysis (eg, Glucostix) of the fluid for glucose and protein – unreliable in determining the presence of CSF fluid
• Presence of beta-2 transferrin indicates CSF leakage (high specificity) – 0.5 cc fluid required to perform test
  • If positive, perform high resolution CT (HRCT) to identify area of leak
  • If negative but strong suspicion, perform HRCT, followed by MRI cisternogram
  • False positives suggest chronic liver disease or inborn errors of glycoprotein metabolism

Imaging Studies

• HRCT – initial study of choice
• MRI or MRI  cisternogram – cisternogram is the procedure of choice
• Cisternogram by CT
• Radiographic studies, with or without intrathecal injection of dye or radioisotope – not always successful in demonstrating small or delayed CSF leaks

Clinical Background

The leakage of cerebrospinal fluid (CSF) into nasal, oral, or ear cavities, or leakage from a dermal sinus and its subsequent drainage from these cavities, may be the result of trauma, intracranial surgical procedures, infection, hydrocephalus, congenital malformations, or neoplasms. The most severe consequence of a CSF leak is microorganism contamination and the development of meningitis.

Epidemiology

• Prevalence – 70-80% are related to accidental trauma
  • 2-4% of head injuries result in CSF leaks
• Age – middle age for spontaneous leaks; newborn for dermal sinus leakage
• Sex – M<F for spontaneous leaks

Etiology

• Trauma
• Nontraumatic
  • Surgery – usually spinal or neurosurgery
    • Postoperative defect
  • Infection
  • Tumor obstruction
  • Congenital defects at the base of the skull or at the end of the spinal cord
  • Hydrocephalus
  • Spontaneous – no known defect or trauma

Pathophysiology

• Beta-2 transferrin, a protein produced by neuraminidase activity in the brain – uniquely found in CSF and perilymph fluid
• Interruption of the anterior cranial fossa floor allows leaks of CSF through the cribriform plate
• 80% of posttraumatic leaks occur ≤48 hours posttrauma
• Presence of beta-2 transferrin in nasal or ear fluid highly suggestive of CSF leak

Clinical Presentation

• CSF leakage most commonly presents as otorrhea or rhinorrhea
• Patient may complain of salty or sweet taste
• Intermittent clear nasal discharge exacerbated by Valsalva maneuver
  • Most often unilateral drainage
• Presence of halo sign on used tissues or bed linen

Indications for Laboratory Testing

• Tests generally appear in the order most useful for common clinical situations
• Click on number for test-specific information in the ARUP Laboratory Test Directory